Search results
Results From The WOW.Com Content Network
The egg is not retained in the body for most of the period of development of the embryo within the egg, which is the main distinction between oviparity and ovoviviparity. [1] Oviparity occurs in all birds, most reptiles, some fishes, and most arthropods. Among mammals, monotremes (four species of echidna, and the platypus) are uniquely oviparous.
The egg cell is generally asymmetric, having an animal pole (future ectoderm). It is covered with protective envelopes, with different layers. The first envelope – the one in contact with the membrane of the egg – is made of glycoproteins and is known as the vitelline membrane (zona pellucida in mammals).
Oviparity: fertilisation is internal, but the female lays zygotes as eggs with a substantial quantity of yolk to feed the embryo while it remains in the egg. The egg is not retained in the body, or only for a limited time. [1] Oviparity is found in insects, birds. Among mammals, the monotremes are oviparous.
For mother cows to continue producing milk, they give birth to one calf per year. If the calf is male, it is generally slaughtered at a young age to produce veal. [106] Cows produce milk until three weeks before birth. [103] Over the last fifty years, dairy farming has become more intensive to increase the yield of milk produced by each cow.
They hold the eggs internally for several weeks, providing nutrients, and then lay them and cover them like birds. Like marsupial " joeys ", monotreme " puggles " are larval and fetus-like, [ 9 ] as like them they cannot expand their torso due to the presence of epipubic bones, forcing them to produce undeveloped young.
So, the short version of this debate: Dairy is milk, milk comes from mammals (like cows), and eggs come from chickens (birds). Therefore, they're not dairy. There you go.
An aphid giving viviparous birth, an unusual mode of reproduction among insects. In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juvenile that is at least metabolically independent.
Here is every type of economic system out there explained with cows: Posted by Mike Hosking. Cows are being used for way more than making milk. From protests like the one above, all the way to ...